In addition to the five suspects held in London, the other two arrests took place in Horley in Surrey and Didcot in Oxfordshire.
It is believed that many migrants were brought into hiding behind furniture in vehicles hired specifically to smuggle illegal people using a network with connections across Europe.
Migrants were paying up to £ 25,000 to be brought in and many were said to have worked in the illegal economy once in Britain.
But after six different attempts were foiled by border force personnel at the Coquelles terminal near Calais and two more were arrested before reaching the coast, the criminal group behind the trafficking was discovered.
Seven members, including three inmates at Purley, one inmate in Morden and another in Croydon, have now been arrested in raids involving more than 100 officers from the National Crime Agency, Met and Home immigration police teams Office.
Around £ 30,000 in cash was also seized, although the NCA has said the scale of the gang’s activity has potentially involved hundreds of thousands of pounds in turnover.
All suspects are being questioned on suspicion of offenses, including conspiracy to facilitate illegal entry into the UK and money laundering.
NCA Commander Richard Harrison said the gang had risked the safety of illegal migrants and threatened the security of the UK border with their illegal activities.
“We believe these arrests will have significantly disrupted an organized criminal network responsible for the illegal entry of hundreds of people into the UK,” he said.
“The network claimed to provide a premium service and billed accordingly, using accomplice drivers to transport migrants in rented vehicles. “
NCA Deputy Director Andrea Wilson added, “Smugglers are at the top of the NCA target list.
“It’s a form of crime that sees people exploited for profit by criminals who have no respect for human life.
“Our agents are working around the clock with partners in the UK and overseas to track them down, disrupt and dismantle their business models and bring them to justice.
“I also have a message today for drivers, commercial or not, who may consider helping these organized criminal networks by transporting migrants on their behalf.
” Do not do that. The penalties for those caught are severe and life changing. It just isn’t worth the risk. “
The arrests are the latest in a series of raids and arrests against Albanian criminal gangs operating in Britain.
The NCA has previously said it believes Albanian organized crime groups control the illegal cocaine market in virtually all major cities in that country, and are also involved in other criminal activities such as human trafficking. .